|Period||Middle and late Jurassic 152-145 million years ago|
|Location||North America,Africa and Europe|
|Length||25-30m long, 13m tall, 35-60 tons|
One of the largest dinosaurs, Brachiosaurus lived in the Middle to Late Jurassic Era and used its unique advantage of a long neck to reach to the leaves in the tallest trees for grazing. Due to its large size, it had few natural predators. The name Brachiosaurus means 'arm lizard' and is estimated to weigh around 40 tons. If dinosaurs were warm-blooded, it would have to eat around 182kg (400lbs) of food a day. Brachiosaurus was found in the late Jurassic and was found in Algeria, Portugal, Tanzania and USA. There were even bigger than Apatosaurus but smaller than Argentinosaurus.The first fossil was discovered in 1900 later a another one was founded in 1902 then named in 1903. There is one species of Brachiosaurus discovered, and it have been called Brachiosaurus altithorax.
Its name relates to its forelimbs, which were longer than its hindlimbs, like its others family members. This causes its neck was upright, like a modern giraffe. The brachiosaurus probably had this long legs for reaching tall trees, and with them, it was also able to overcome huge obstacles. Curiously, this legs were very thin, so this big herbivore couldn't walk or run very fast. However, with the neck upright, it was 13m tall, so it was probably that carnivores didn't attack it because of its incredible size. The brachiosaurus also had a short tail(to balance the body) and, like other sauropods, a skull with a long snout, with holes to reduce weight. It had large air sacs connected to the lung system were present in the neck and trunk, invading the vertebrae and ribs, greatly reducing the overall density.
The genus Brachiosaurus, and type species B. altithorax, are based on a partial postcranial skeleton from Fruita, in the valley of the Colorado River of western Colorado. This specimen was collected from rocks of the Brushy Basin Member of the Morrison Formation in 1900 by Elmer S. Riggs and his crew from the Field Columbian Museum of Chicago. In 1899 Riggs had sent inquiries to rural locations in the western United States concerning fossil finds, and Bradbury, an amateur collector himself, reported that dinosaur bones had been collected in the area since 1885. It was Riggs' field assistant H. W. Menke who found the skeleton on July 4, 1900. Additional Brachiosaurus fossils are reported on Riggs Hill, but other fossil finds on the hill have been vandalized. Riggs published a short report in 1901, noting the unusual length of the humerus compared to the femur and the extreme overall size and the resulting giraffe-like proportions, as well as the lesser development of the tail, but did not publish a name for the new dinosaur. The titles of Riggs (1901) and (1903) suggested that the specimen was the largest known dinosaur. Riggs followed his 1903 publication that named Brachiosaurus altithorax with a more detailed description in a monograph in 1904. The Fruita skeleton was not the first discovery of Brachiosaurus bones, although it was the first to be recognized as belonging to a new and distinct animal. In 1883, a sauropod skull was found near Garden Park, Colorado, at Felch Quarry 1, and was sent to Othniel Charles Marsh. Marsh incorporated the skull into his skeletal restoration of "Brontosaurus" (now Apatosaurus). It eventually became part of the collections of the National Museum of Natural History. In the 1970s, when Jack McIntosh and David Berman were working on the issue of the true skull of Apatosaurus, they reevaluated the Garden Park skull as more similar to Camarasaurus. It was described and recognized as a Brachiosaurus skull in 1998 by Kenneth Carpenter and Virginia Tidwell, intermediate in form between Camarasaurus and Giraffatitan brancai (then still considered to be Brachiosaurus brancai). Because there are no overlapping parts between this skull and the discovered in 1900, it cannot be confidently assigned to a species, so it is classified as Brachiosaurus.Additional discoveries of Brachiosaurus material in North America have been uncommon and consist of a handful of bones. Material has been described from Colorado, Oklahoma, Utah, and Wyoming, and undescribed material has been mentioned from several other sites. The Giraffatitan material(from Tengaduru in 1914) was considerated firstly as B. altithorax, but describing the "brachiosaurid" material, Janensch listed a number of differences and commonalities between them and B. altithorax. In three further publications in 1929, 1950 and 1961 Janensch compared the two species in more detail, listing 13 putative shared characters. Of these, however, only four appear to be valid, while six pertain to more inclusive groups than Brachiosauridae, and the rest are either difficult to assess or refer to material that is not Brachiosaurus.In 1988, Gregory Paul published a new reconstruction of the skeleton of "B." brancai, highlighting a number of differences in proportion between it and B. altithorax. Chief among them is a difference in the way the trunk vertebrae vary: they are fairly uniform in B. altithorax, but vary widely in the African material. Paul believed that the limb and girdle elements of both species were very similar, and therefore suggested to separate them not at genus, but only at subgenus level. Giraffatitan was raised to genus level by Olshevsky without comment. A detailed study of all material, including the limb and girdle bones, by Michael Taylor in 2009 found that there are significant differences between Brachiosaurus altithorax and the Tendaguru material in all elements known from both species. Taylor found 26 distinct osteological (bone-based) characters, a larger difference than that between, for example, Diplodocus and Barosaurus, and therefore argued that the African material should be placed in its own genus, Giraffatitan, as G. brancai. An important difference between the two genera is the overall body shape, with Brachiosaurus having a 23% longer dorsal (trunk) vertebrate series and a 20 to 25% longer and also taller tail.
With the removal of the East African Giraffatitan, Brachiosaurus is known only from the Morrison Formation of western North America. The Morrison Formation is interpreted as a semiarid environment with distinct wet and dry seasons, and flat floodplains. Vegetation varied from gallery forests (river–lining forests in otherwise treeless settings) of conifers, tree ferns, and ferns, to fern savannas with rare Araucaria-like trees. Several other sauropod genera were present in the Morrison Formation, with differing body proportions and feeding adaptations. Among these were Apatosaurus, Barosaurus, Camarasaurus, Diplodocus, Haplocanthosaurus, and Supersaurus. Brachiosaurus was one of the less abundant Morrison Formation sauropods. Brachiosaurus fossils are found only in the lower-middle part of the expansive Morrison Formation (stratigraphic zones 2-4), dated to about 154-153 million years ago, unlike many other types of sauropod which have been found throughout the formation.